A separator for use in a fuel cell has a seal made of silicon rubber molded to its periphery. As this kind of seal, for example Japanese Patent Laid-Open Publication No. 11-309746 (JP-A-11-309746), “Manufacturing Method of Silicone Resin—Metal Composite” is known. This manufacturing method of related art will be described on the basis of FIG. 28.
By an injection-molding apparatus 500 being closed, a separator proper (that is, plate-shaped member) 503 is inserted between a fixed die 501 and a moving die 502 and a cavity 504 is formed by the fixed die 501 and the moving die 502.
Molten silicone resin is injected into the cavity 504 as shown with an arrow. By this means, a front side seal (that is, molded layer) 506 is molded to the front side 505 of the separator proper 503, and seal material is made to flow around to the rear side 507 of the separator proper 503 so that a rear side seal 508 is molded.
The front side seal 506 and the rear side seal 508 together constitute a seal 509 covering a peripheral part 503a of the separator proper 503. By a seal 509 being formed on the peripheral part 503a of a separator proper 503 like this, a separator 510 is obtained.
By sandwiching an electrolyte membrane, a negative electrode and a positive electrode with this separator 510, a fuel cell is assembled. Because hydrogen gas, oxygen gas and product water flow inside this fuel cell, it is necessary for the seals of the separator to be molded well.
Here, the seal 509 is a molded membrane made of thin silicone resin, and when the molten silicone resin is injected into the cavity 504, it takes time for the front side seal 506 to be molded to the front side 505 of the separator proper 503 and for the molten silicone resin to flow around to the rear side 507 of the separator proper 503 well.
Consequently, the manufacture of the separator 510 takes time, and this has been an impediment to raising the productivity of fuel cells.
Also, when the cavity 504 is being filled with silicon resin, to make the silicone resin flow around to the rear side 507 of the separator proper 503 from the front side 505, for example an injection pressure of the silicone resin may act only on the front side 505 of the separator proper 503.
Therefore, when the separator proper 503 is a very thin plate material, there is a risk of the injection pressure of the silicone resin acting only on the front side 505 side being too great with respect to the rigidity of the separator proper 503. Consequently, it is necessary for the injection pressure of the silicone resin to be kept down, so that an excessive injection pressure does not act on the separator proper 503.
However, when the injection pressure of the silicone resin is kept down, the manufacture of the separator 510 takes time, and this has been an impediment to raising the productivity of fuel cells.